Understanding your ovarian reserve

The term ‘ovarian reserve’ is commonly used by fertility specialists. It forms an important part of the female fertility assessment. This reflects the fertility reserves of your ovaries and has implications on your chances of getting pregnant naturally or with treatment.

Women are born with around 4-5 million eggs which remain in quiet stage until puberty. During this period, there is a slow, but steady loss of the follicles. Only 400,000 – 500,000 follicles remain by puberty.

What leads to low ovarian reserve?

Since birth, there is a decrease in quality and quantity of eggs that carries on at a slower pace. This gathers pace around the age of 35 years and decreases rapidly in 40’s.

The reduction in the egg quality and quantity is a natural phenomenon and contributes to the delay or failure when trying to conceive. It also reduces the chance of you getting pregnant following a fertility treatment, such as IVF or Insemination. There are certain medical or gynaecological conditions that may lead to low ovarian reserve in younger women. Examples include:

Endometriosis
Pelvic infection
Tubo-ovarian surgery
Removal of ovary
Past history of treated cancer
Medical conditions treated with medicine that might be damaging to ovaries
Autoimmune causes
Family history of premature menopause or infertility
Carrier of fragile X mutation
Smoking, etc.

In some women, there might be no obvious identifiable reason.

How can we check ovarian reserve?

The best marker for the quality of the eggs is the women’s age. The best way to assess the ovarian reserve is by using a combination of blood tests and ultrasound scans.

Some of the tests to assess ovarian reserves are:

Anti-Mullerian hormone (AMH) level
Follicle Stimulating Hormone (FSH)
Inhibin B
Clomiphene citrate challenge test (CCCT)
Antral Follicle Count (AFC)

None of these tests alone will give a reliable answer. Therefore, it is usually recommended that a combination of tests are used when assessing the ovarian reserve.

What is AMH, FSH, Estradiol, Inhibin B and AFC

The AMH is a hormone that is produced by cells surrounding the dormant follicles. The levels of AMH remain steady irrespective of the day of the menstrual cycle. Hence the test can be done any time in the menstrual cycle.

A lower value of AMH will be indicative of the reduction in reserves. The lower the AMH value, the lower the reserve and the chance of getting pregnant when trying naturally, or with fertility treatment.

FSH is a hormone produced by a small gland in the brain called pituitary gland and it regulates the function of the ovaries. This test happens between day 2–4 of the menstrual cycle. Usually, the blood Estradiol levels are checked along with FSH for more accurate results.

The higher the FSH value, the lower the ovarian reserve. Like AMH, this would imply a decrease in the ovarian reserve, delaying conception or reducing the success rate following fertility treatment.

The Inhibin B is secreted by the cells surrounding the dormant follicles.
The levels may fluctuate and is usually not recommended as a reliable marker for assessing ovarian reserve.

Antral Follicle count or AFC is the number of small follicles in both ovaries. These are the follicles that are recruited for development in a natural cycle and lead to the dominant follicle that results in ovulation.

There is no single test in isolation that can give a 100% accurate answer. Therefore, specialists usually use a combination of tests to improve the predictive power and reliability of the assessment.

How does ovarian reserve affect female fertility?

Having understood the tests necessary to evaluate the ovarian reserve, we should also understand the mechanism that leads to a reduction in fertility.

Generally, the quality refers to both the reduction in quantity and quality. There is no clinically available diagnostic test that can accurately analyse these two parameters.

Eggs of poor quality experience a higher chance of error during the cell division and splitting of the genetic material between the cells. This creates a genetically abnormal embryo that the womb might prevent from implanting. It may also lead to miscarriage if it has managed to implant. So women with reduced ovarian reserve may also experience higher miscarriage rate.

What are my options if I have low ovarian reserve, low AMH, or high FSH?

It is important to stress that low ovarian reserve does not necessarily mean that you can never get pregnant. For some women, it may mean that it may just take longer when trying to get pregnant.

If you have been unsuccessful for some time, then you should see a fertility specialist for further advice. For others going through fertility treatments such as IVF, they may experience lower IVF success rates.

In a small proportion of women with very low ovarian reserve, they may have to consider using donor eggs to help get pregnant. In that case, the window of opportunity for trying naturally or with treatment is shorter, and they should seek early advice.

If I have low AMH or low ovarian reserve, am I menopausal?

No, low ovarian reserve does not imply that you are going through menopause or are perimenopausal. It simply indicates your fertility potential.

Women with reduced ovarian reserve usually have a regular cycle but have a lower chance of getting pregnant per menstrual cycle (also known as fecundity). However, if you do experience absence of menstrual cycles or irregular cycles, then you should consider seeing your doctor or gynaecologist.